Non Destructive Testing of Steels Non destructive testing (NDT) of steels is a group of analysis techniques used for evaluating the properties of steel materials, components, or welds without causing any damage to them. NDT techniques are used to detect and evaluate internal and surface defects (such as imperfections, discontinuities, and flaws etc.) that may cause failure under the designed operating conditions. These internal and surface defects may be the areas of lower integrity in comparison to other portion of the steel material or may consists of the presence of cracks, voids and other imperfections. NDT gives indirect yet valid results and, by definition, leave the test object fit for its intended use. The terms non destructive examination (NDE), non destructive inspection (NDI), and non destructive evaluation (NDE) are also used for these testing techniques. Since there is no permanent alteration in the steel material being tested by NDT techniques, the NDT techniques are considered very important for material inspection. NDT saves both money and time in product evaluation, troubleshooting, and research. NDT techniques constitute very specialized type of work that plays a critical function. These techniques need the service of highly specialized and qualified technicians who use sophisticated equipment and methods to evaluate areas of the steel component that are difficult or impossible to examine using the naked eye. The NDT techniques are used for detecting defects during manufacture and fabrication as well as the defects developed during service of the steel components. However, it is not possible to detect all the possible defects by examining a component by NDT. Further in NDT, it is not the defect that is detected but the resulting effect on the material such as the modification of physical properties (attenuation to ultra sound or the electrical conductivity etc.). NDT techniques do not provide direct information...